Final Exam - Equine Orbit, Eyelids, & Lacrimal Glands Flashcards
what are some ways you can assess vision in a horse?
stationary object avoidance with a blindfold over the good eye
menace response
pupillary & dazzle response
what is the number one test for assessing vision in a horse?
DAZZLE RESPONSE!!!!
what are you looking for on ultrasound of an equine eye if you are concerned about vision or other issues?
looking at the pupil size & looking for retinal detachment
if concerned about vision deficiencies in a horse, what should you do prior to sedation?
need to assess the reflexes
what are clinical signs associated with orbital trauma in horses?
asymmetry of periocular structures, prominent 3rd eyelid, epiphora, emphysema, & unilaterally reduced airflow
_____ & ______ are more susceptible to traumatic fracture of the bony orbit
horses & cattle
how is orbital trauma diagnosed?
complete physical, neurologic exam, & ophthalmic exam - rads, ultrasound, & CT/MRI
what treatment is indicated for orbital trauma? what affects prognosis?
conservative medical management if non-displaced
surgical correction
prognosis depends on severity of trauma!
where do eyelid lacerations most commonly occur in horses?
lateral to medial tear is most common - upper lid is most likely
what is the required treatment for eyelid laceration? why?
surgical repair - essential to avoid exposure & development of keratitis
what is the essential treatment indicated for periocular squamous cell carcinomas?
debulking is essential followed by cryotherapy, hyperthermia, chemo, piroxicam, or photodynamic dye therapy
when do we see periocular habronemas in horses?
occurs in the humid summer months
what is the vector of habronemiasis? what is the pathophysiology of it?
horse & stable flies
adult habronema live in the equine stomach & larvae in feces are picked up by fly larvae
infective habronema larvae are deposited near mucocutaneous junctions or on skin wounds caused by adult flies
what treatment is used for ocular habronemiasis in horses?
topical insecticide ointment, fly control, systemic ivermectin, & anti-inflammatories (nsaids or steroids)
what is the most common ocular abnormality recognized in foals? why?
entropion - due to loss of periorbital fat or dehydration
how is entropion corrected in foals?
temporary stay sutures
wedge technique used for permanent correction
temporary injectable
where are the most common locations for ocular squamous cell carcinomas in horses?
scleral, corneal, or both
what is the ideal treatment used for equine ocular squamous cell carcinomas? why? how is it used & what are the risks?
debulking + strontium-90 irradiation is ideal
it doesn’t harm inner structures of the globe & no residual radiation is left
need 1-3 applications at 30 day intervals
risks - can cause ulcers to heal slowly
what medical treatment is used for periocular sarcoids in horses?
chemotherapy - 5-F cisplatin
immunotherapy
irritants to cause immune reaction
what are your treatment options for equine periocular sarcoids?
medical
surgical excision
cryotherapy
radiation - iridium implants
mitomycin C & acyclovir
what is exophthalmos?
normal sized globe is pushed out by periocular tissues that can lead to exposure keratopathies
what are the main causes of exophthalmos in horses?
inflammation/cellulitis
neoplasia
cystic mass
T/F: blockage of the nasolacrimal duct will result in epiphora
true
what is different about the nasolacrimal ducts in donkeys when compared to horses?
in donkeys, they are located on the lateral aspect!!! not medial!!!
